Insulating implement for use in a microwave oven



Nov 10, 1970 M. L. LEVINSON 3,539,751

INSULATING IMPLEMENT FOR USE IN A MICROWAVE OVEN Filed 001;. 26, 1966 2 Sheets-Sheet l United States Patent 3,539,751 INSULATING IMPLEMENT FOR USE IN A MICROWAVE OVEN Melvin L. Levinson, 1 Meinzer St., Avenel, NJ. 07001 Filed Oct. 26, 1966, Ser. No. 589,626 Int. Cl. H05b 5/00, 9/06 US. Cl. 219-1055 13 Claims ABSTRACT OF THE DISCLOSURE An insulating implement for use with apparatus employing electromagnetic wave irradiation. The implement includes a microwave permeable body having a cavity therein formed by a plurality of surfaces, at least one of the surfaces being heat reflective. The cavity has disposed therein a heat insulator, such as a vacuum.

BRIEF DESCRIPTION Electromagnetic wave irradiation in the microwave region is daily becoming more important in processing. In my copending application, A Heating and Loading Implement for Devices Employing Microwave Energy Radiated into a Closed Cavity, Ser. No. 470,809, filed July 9, 1965, now abandoned in favor of my continuation-in-part application, Ser. No. 704,389, filed Feb. 9, 1968, I described means for releasing heat in a microwave oven. In my copending application A Heat Equalizing and Directing Means for Heating Implements used in Microwave Ovens, Ser. No. 483,144, filed Aug. 27, 1965, now abandoned in favor of my continuation-in-part application, Ser. No. 704,389, filed Feb. 9, 1968, I described means to direct the microwave energy and control the distribution of the heat released in my heating implement. In this present invention I will describe new ways to contain heat generated by and converted from microwave energy, and will describe novel methods of using my innovations together.

One object of this invention is to create a new implement, useful in processing materials employing electromagnetic wave irradiation in the microwave region.

Another object of this invention is to create new cooking and heat retaining utensils for food processed in a microwave oven.

Another object of this invention is to better contain the heat generated in a lossy useful load and/or better to utilize the heat generated in a lossy substance exposed to microwave energy which in turn heats a microwave permeable load by conventional heat transfer.

Another object of this invention is to provide insulating walls and insulating structures for use in my Microwave Kiln, copending patent application Ser. No. 497,851, filed Oct. 19, 1965, now Pat. No. 3,469,053.

Another object of this invention is to make novel cooking utensils for use in microwave cooking.

Another object of this invention is to provide a new removable bottom tray for microwave ovens, and new shelves for microwave ovens.

I utilize certain of the excellent properties of the new crystallized type glass-ceramic material exemplified by Cornings Pyroceram and Owens-Illinois Cer-Vit mate rials. The properties most desirable for this invention are transparency to microwave energy, strength, low thermal conductivity, whiteness, for reflecting heat, low porosity to gases, hard finish for easy cleaning, and high resistance to temperature shock. Other materials such as quartz may be used. Preferably my insulating implement is made of a heat reflective material which is easy to clean and difficult to destroy, a material which in itself is permeable to and not wasteful of microwave energy. The basic low thermal conductivity of the material used in forming my insulating implement is further enhanced by confining selectively within this implement another material of still lower thermal conductivity such as conventional insulating material, dry air, or preferably a vacuum.

In the accompanying diagrams:

FIG. 1 is a plan view of an insulating implement.

FIG. 2 is a side view of FIG. 1.

FIG. 3 illustrates one embodiment of my implement and depicts a cross sectional view of my insulating implement A holding a heating and loading implement B, more fully described in my aforementioned application Ser. No. 704,389, which in turn holds a load and another insulating implement A in an inverted position.

FIG. 4 illustrates various embodiments of using implernentS.

FIG. 5 is a cross-sectional view of the insulating implement having utility as a shelf for a microwave oven; an insulating wall for a microwave kiln; or a removable cleanable tray which is designed to lie on the bottom of a microwave oven.

FIG. 6 is a cross section view of insulating implement taken along the line 6-6 of FIG. 5.

FIG. 7 is a cross-sectional view of one embodiment of forming one insulating dish from two pieces, prior to being joined together.

FIG. 8 shows the two pieces of FIG. 7 joined together to form one dish.

I do not wish to be limited to these few configurations, as anyone skilled in these arts could readily make changes without the use of invention. In fact this invention is concerned with improved dishes useful in microwave ovens by building within said dishes a cavity which preferably contains a vacuum or other insulating means therein as stated above.

DETAILED DESCRIPTION FIGS. 1 and 2 illustrate two views of one type insulating implement. My implement is provided with a rim 1 which is shown corrugated as one means to permit stacking rim to rim to achieve a stable stack as shown in FIG. 3. The implement includes side walls 2 and a working surface 3 for holding a load 7 requiring processing. Located beneath working surface 3 is a cavity 4 provided with an access opening 5 for introducing a heat insulating material or vacuum which is sealed with a plug 6 to form a liquid or gas proof seal.

In FIG. 3 there is shown an insulating implement A, similar to said implement just described, which is cooperatively associated with a heating implement B of the type found in my said application, Ser. No. 704,389. Both of these implements are best constructed of a glass-ceramic which will withstand high temperatures and high thermal shocks. Both implements A and B may differ in one respect, namely, in heating implement B the cavity 8 is filled with a material which converts microwave energy into heat energy, and in the insulating implement A the cavity 4 is filled with a material, preferably a vacuum, which is unaffected by microwave energy and is a better heat insulator than its container. Side walls 11 and walls 9 and 10 of cavity 4 are indicated.

Still, with reference to FIG. 3, the insulating implement A is used to hold a mating heating implement B so that implement A may minimize the heat loss and may would be lost emanating from load 7 by radiating through the material or vacuum in cavity 4 is not lost as it is reflected back to load 7 by wall 9 of cavity 4 being heat reflective. Hence, the insulating implement A is useful to minimize heat loss by load 7 during the emission of microwave energy.

Said another way, similar mating implements, one insulating implement A and one heating implement B, can be combined, stacked and used in many useful groupings. FIG. 4 shows a representative sample of such groupings. The examples shown schematically in FIG. 4 are as follows:

(a) Insulating dish A holding load C;

(b) Insulating dish A hold a heating dish B holding a load C;

(c) Insulating dish A holding a load C which is heated from the top by heating dish B;

(d) Load C confined between two insulating dishes A and A;

(e) Insulating dish A holding a heating dish B holding a load C covered by insulating dish A;

(f) Insulating dish A holding load C. Load C covered and heated by heating dish B whose heat is directed and confined by insulating dish A; and

(g) The insulating action or the heating action can be multiplied by using multiple implements-two insulating dishes A and A holding two heating dishes B and B holding load C.

FIGS. 5 and 6 illustrate another embodiment of this invention having utility as a removable, cleanable bottom tray for a microwave oven. This insulating tray besides its insulating properties (which keeps the heat generated in the load from being lost through the bottom metallic surface of the oven) positions the load high enough from the bottom surface of the oven to subject the load to the active microwave field. Illustrated are integral supporting structures 18 for providing additional strength when a vacuum is employed. This tray can be made of two separate pieces and fastened together by member 12.

My insulating implement in the configuration of a shelf for a microwave oven will conserve the amount of power needed to heat a load, versus a normal shelf which acts as a fin to dissipate heat.

My insulating implement could also be made in the configuration of a wall (FIGS. 5 and 6) or a brick (not shown) to improve the construction of my microwave kiln described in my aforementioned copending application, Ser, No. 497,851. These novel microwave oven walls and bricks may be used alone or in conjunction with other conventional insulating material.

As seen in FIG. 7, similar heating and insulating dishes as described may be constructed from halves of two complementary molds. FIG. 7 and FIG. 8 illustrates two mating halves 13 and 14 which together make one dish. The dish rims 15-15 are sealed at (FIG. 8) to form a cavity 4' within the dish. If sealed at high temperature rarefied dry air would be trapped in this cavity 4' to ultimately become the insulating element in the insulating dish A. The heating dish B would be constructed by filling the cavity with a suitable lossy material and the two halves sealed at rim 15. The cavity 4' need not cover the whole inside area of the dish or be centrally or symetrically placed, but may be selectively placed to enhance some cooking function. So, in cooking two unequally heating loads on one plate, a slower heating load, not shown, may be placed on the insulating portion of the dish and a faster heating load, not shown, on the regular portion of the dish to achieve planned even heating. A heat directing and equalizing shield 16 can be located in cavity 4 on option. This shield 16 could be made of radiant heat reflecting material.

A glass-ceramic which can withstand extreme temperature shocks is recommended for an insulating dish used in conjunction with my heatin dish because of the 4 practice of precharging a heating dish with heat prior to using it to sear frozen meat.

With the foregoing and other objects in view, the invention resides in the novel arrangement and combination of parts and in the details of construction here described and claimed, it being understood that changes in the precise embodiment of the invention here disclosed may be made within the scope of what is claimed without departing from the spirit of the invention.

I claim:

1. An insulating and heating implement for use with apparatus employing electromagnetic wave irradiation in the microwave region, which comprises:

a first body having a cavity therein which is formed by a plurality of heat reflective surfaces,

a second body in contact with said first body and having a cavity therein, said second body capable of holding a workload,

a plurality of resistive particles located within said second body cavity, which when exposed to microwave irradiation, results in a multitude of arcs being generated therethrough so as to convert microwave energy into heat energy, and

a third body having a cavity therein which is formed by a plurality of heat reflective surfaces, said first, second and third bodies being constructed of microwave permeable material, said third body being so disposed with said first body that the surfaces are capable of reflecting the generated heat energy towards and away from each other, thereby permitting a maximum amount of heat energy to remain within the implement to heat the workload.

2. An insulating and heating implement according to claim 1 wherein the first body cavity is evacuated.

3. An insulating. and heating implement according to claim 1 wherein the third body cavity is evacuated.

4. An insulating and heating implement according to claim 1 wherein said first body cavity is provided with a heat insulating material.

5. An insulating and heating implement according to claim 1 wherein said first body cavity is provided with a heat insulating material.

6. In a microwave oven comprising a chamber for receiving a workload and means for emitting microwave energy to said workload, for use in said oven, an improved, heat-insulating implement, in the form of an oven wall, for confining heat generated from said microwave energy, said improved, heat-insulating implement comprising in combination:

a body constructed of a material for permitting the passage of microwave energy therethrough, said body having a cavity therein formed by a plurality of surfaces wherein at least one of said surfaces is A relatively more heat reflective than heat absorptive for impeding radiant heat loss, and

a microwave permeable heat insulator disposed within said cavity for impeding the passage of conductive and convective heat flowing through said cavity.

7. In a microwave oven, according to claim 6, wherein the cavity is evacuated.

8. In a microwave oven comprising a chamber for receiving a workload and means for emitting microwave energy to said workload, for use in said oven, an improved, heat-insulating implement, in the form of an oven shelf, for confining heat generated from said microwave energy, said improved, heat-insulating implement comprising in combination:

a body constructed of a material for permitting the passage of microwave energy therethrough, said body having a cavity therein formed by a plurality of surfaces wherein at least one of said surfaces is relatively more heat reflective than heat absorptive for impeding radiant heat loss, and

a microwave permeable heat insulator disposed within said cavity for impeding the passage of conductive and convective heat flowing through said cavity.

9. In a microwave oven, according to claim 8, wherein the cavity is evacuated.

10. In a microwave oven comprising a chamber for receiving a workload and means for emitting microwave energy to said workload, for use in said oven, an improved, heat-insulating implement, in the form of a utensil for holding said workload, for confining heat generated from said microwave energy, said improved, heat-insulating implement comprising in combination:

a body constructed of a material for permitting the passage of microwave energy therethrough, said body having a cavity therein formed by a plurality of surfaces wherein at least one of said surfaces is relatively more heat reflective than heat absorptive for impeding radiant heat loss, and

a microwave permeable heat insulator disposed within said cavity for impeding the passage of conductive and convective heat flowing through said cavity.

11. In a microwave oven, according to claim 10, wherein the cavity is evacuated.

12. In a microwave oven comprising a chamber for receiving a workload and means for emitting microwave energy to said workload, for use in said oven, an improved, heat-insulating implement, in the form of a tray, for confining heat generated from said microwave energy, said improved, heat-insulating implement comprising in combination:

a body constructed of a material for permitting the passage of microwave energy therethrough, said body having a cavity therein formed by a plurality of surfaces wherein at least one of said surfaces is relatively more heat reflective than heat absorptive for impeding radiant heat loss, and

a microwave permeable heat insulator disposed within said cavity for impeding the passage of conductive and convective heat flowing through said cavity.

13. In a microwave oven, according to claim 12, wherein the cavity is evacuated.

References Cited UNITED STATES PATENTS 819,650 5/1906- Harden 2l9436 2,486,964 11/ 1949 Miller 3 l762 3,429,359 2/1969 Hollingsworth 164-50 3,469,053 9/1969 Levinson 219-l0.55

FOREIGN PATENTS 333,015 6/1903 France.

JOSEPH V. TRUHE, Primary Examiner L. H. BENDER, Assistant Examiner U.S. Cl. X.R. 

